Method of making pistons



C. H. KIRBY METHOD OF MAKING PISTONS March 3o, 1926. 1,578,323

Filed May 2l. 1923 .Imm/ffm 4 m M alibi-M10 Patented Mar. 30, 1926.

UNITED STATES CHARLES H. KIRBY, OF DETROIT, MICHIGAN'.

lamanon'v or MAKING PIsroNs.

Application med nay ai, 1923. serial No. 640,565.

To all whom t may concern Be it known that I, CHARLES H. KIRBY, a citizen of the United States of America, residing at Detroit, in the county of Wayne and tate of Michigan, have invented certain new and useful Improvements in Methods of Making Pistons, of which the following is a specification, reference being had therein to the accompanying drawings.

This invention relates to pistons of the type in which the skirt is longitudinally slotted to produce lightness and interally ribbed to secure the necessary strength. Such pistons have proved very satisfactory under operating conditions but the cost of manufacture has been higher than with the continuous skirt type because of the difficulty in machinin This is due primarily to the lack of rigidity in the skirt portion of the piston casting because of the thin section of the metal and the interrupted peripheral surface.

To overcome this machini g difficulty I have formed the casting wit an integral ring forming an extension of the skirt, thereby increasing the rigidity and providing a continuous annular surface which can be readily supported in a lathe. The casting is then com letely machined and in the last operation t e ring is removed leaving the nished piston with the divided skirt.

In the drawings Figure 1 is a longitudinal section of a finished piston;

Figure 2 is a bottom plan view thereof;

Figure 3 is a sectional elevation of the piston casting;

Figure 4 is a sectional elevation at right an les thereto;

igure 5 is a plan view of a double piston casting.

Figures 1 and 2 show a piston having the head A and the divided skirt portions B and B. The piston is provided with bosses C extending transversely of the divided skirt ortion and the structure is strengthened y means of the internal ribs D.

Figures 3 and 4 represent the cast blank from which the piston above described may be machined. This blank mayT be cast in the usual manner with the longitudinal slots E, thereby forming the diametrically opposite segmental portions F, but in order to secure rigidity in the casting, I have provided the integral ring G, the outer periphery of which is preferably of the same diameter as the head portion H. By means of the ring G the casting may be supported in the machine at either end and all of the operations for finishing the piston within the de sired degree of tolerance may be performed while the segmental portions are rigidly supported. After the machining has been completed the piston may be supported at the head and the ring G removed thereby forining the piston shown in Figures l and 2. Figure 5 represents a modied piston blank in which a. single casting may be machined to form two finished pistons. In this view the blank I consists of the opposite end portions J and J forming the heads of the pistons, the inwardly extending segmental portions K and K and the central ring L integral with the segmental portions. It will be noted that the blank I may be considered as being made of a pair of blanks, such as shown in Figures 3 and 4, having a common connecting ring. M and M refer to the slots between the segmental portions K and K respectively and 1t is due to these slots that it 1s possible to cast the double piston blank, as shown, because it is necessary to provide a support for the dry sand cores while pouring the metal `in the mold.

The blank I is preferably provided at its opposite ends with axially aligned bosses T and T in order that the blank may be supported upon centers U and U during the machining operations. The centers prefer'- ably extend into the head portions J and J of the blank through drilled holes IV and 'W' and the centers are reduced at X and X to provide a clearance so that the bossesl T and T may be removed after the 'blank is machined. The final operationv of the machine .is to 'separate the blank into the two pistons by removin the ring L.

T he addition of t ie ring integrall formed with the segmental portions in oth the single piston blank and the double blank provides a rigid casting which simpliiies the setting up of the blank in the machines. After all of the operations have been completed to provide a finished piston, the ring may, be removed to leave the flexible segments B and B', as shown in Figures 1 and 2.

What I claim as my invention is 1. The method of fabricating istons which consists in forming a casting aving` a head, segments extendingtherefrom, and an annular portion-alf the opposite ends of said segments,fmachining said casting while said annular portion is integral Itherewith to maintain a rigid structure and subsequently removing said annular portion to obtain a piston having iexible sefgmental portions.

2. The method ofabricatin pistons which consists in forming a` cast lank for a plurality of istons having a pair of heads at opposite en -s-thereof, segmental portions extending. inwardly from said heads and a common annular portion connecting said segments, machining said blank while said annular portion is'integral therewith to maintain rigidity in the structure and subsequently removing said annular portion to obtain a pair of p1stons having flexible segmental portions.

3. A piston blank comprising a head, segmental portions projecting therefrom and an annular portion at the opposite ends of said segments.

4. A piston blank comprising a head, a pair of segmental portions projecting thererom upon diametrically opposite sides of said blank, and an integral ring at the oppo-y site ends of said segments, said ring forming a brace for said segmental portions to maintain rigidity during the machining of said blank and being adapted for removal subsequent to the machining operations to render said segments flexible.

5. A cast blank `for a plurality of pistons comprising a pair o heads at opposite ends thereof, segmental ortions extending longitudinally inward om said heads, and an annular portion connecting said segments intermediate said heads.

6. A piston blank comprising a hollow cylindrical castin' closed at its opposite ends and having longitudinal slots in the sides, said blank bein provided with a pair of integral bosses a jacent each of the opposite ends, and extending inwardly from the side walls, said blankalso being provided with strengthening ribs in the interior thereof.

7. A piston blank comprising a hollow cylindrical casting closed at its opposite ends and provided with a continuous annular portion midway between its ends, the sides o f said cylindrical blank being formed withl longitudinall extending slots between said annular portlon and said closed ends, the inmer surface of said hollow casting being provided with strengthening ribs and having inwardly extending bosses on opposite sides lof said annular portion.

8. -A istonblank comprising a hollow cylindrica casting closed at its opposite ends and fashioned in the hollow interior to rovide inwardly extending bosses and rein orcing ribs, said blank being formed with a continuous annular portion midway between its ends and having slots in the sides between said annular portion and said closed ends and axially arranged bosses rojecting outwardly from the opposite en s of the blank.

9. The method of fabricating pistons which consists in first casting a hollow cylindrical blank closed at the opposite ends and having slots in the cylindrical' sides, machining the exterior of said blank and severing the blank in the middle to obtain two separate cup shaped pistons.

10. The method of fabricating pistons which consists in first casting a hollow cylindrical blank closed at its opposite ends and provided with a continuous annular portion midway between the ends, Ithe blank being formed with slots in-its cylindrical sides between said annular portion and said closed ends, machining the exterior of said blank and subsequently removing the continuous annular portion to form two separa-te cup shaped pistons having flexible segmental portions.

1l. The method of fabricatin pistons which consists in first casting a ho ow cylindrical blank closed at its opposite ends haV- ing a continuous annular portion midway between the ends and slots between said annular portion and said ends, said blank being cast with axially aligned bosses projecting outwardly from the opposite ends, rotating said blank about its longitudinal axis, machining the exterior of said blank during said rotation, removing the bosses and finally removing the annular portion to obtain two separate cup shaped pistons, each havin iiexible se mental portions.

12. he method of fabricating pistons which consists in forming a casting having a 105 head, segments extending therefrom and an annular portion at the opposite ends of said segments, machining said casting while said annular portion is integral therewith to maintain a rigid structure and subsequently 110 removing the annular portion adjacent to the segments to obtain a piston having flexible segmental portions.

, 13. The method of fabricating pistons which consists in forming a blank having a 115 head, segmental ortions extending therefrom and a mem er connecting the other ends of said segmental portions for maintaining the latter in rigid relation to each llOA other, machining said blank while said memopposite ends thereof, segmental vportions remesas4 extending inwardly from each ofA vsaid headsl `machinin said blank while said connecting member 1s integraly therewith to maintain a-rigid structureand subsequently dividing said blank into two .portions and removing said connecting member adjacent said segmental portions to obtain two separate pis- 10 ltons having flexible segmental portions.y

In testimony whereof I aiix my signatnre.

CHARLES KIRBY. 

